This invention relates to a system for presenting the location of a fleet of vehicles to a fleet manager or fleet dispatcher. Specifically, the invention is related to an integrated system which displays a raster map and vectorized display information corresponding to vehicle position.
In the fleet management business, knowledge of vehicle location is a powerful tool for the manager or dispatcher to efficiently operate their fleet. Assimilating the location of the fleet as quickly as possible is critical for efficient decision making. Various navigational systems, including the LORAN system and the Global Positioning System (GPS), are used to reliably determine vehicle location. Both the LORAN and GPS navigation systems rely on externally transmitted radio frequency signals to calculate the location of a receiving antenna mounted on the vehicle. The vehicle position is defined in terms of a latitude and longitude value.
In order for the latitude and longitude values to be easily utilized by the dispatcher, latitude and longitude information is typically displayed in a map format. The two most common map formats for displaying vehicle position are 1) a raster map and 2) a vector map display. FIG. 1 illustrates a raster map display. A raster map is a digitized version of the type of road maps or paper maps most dispatchers are familiar with. A raster map is formed by digitally scanning a standard road map or paper map. Like the standard road map, raster maps typically contain visual features, such as natural and manmade features of the land, contour lines featuring shape and elevation and specific features such as roads, towns, water areas and vegetation.
One prior art raster display system is the MapStation developed by Spatial Data Sciences. MapStation is capable of displaying an icon representative of vehicle position moving along a raster map as the vehicle changes its latitude and longitude position. Since the latitude and longitudinal position of the icon corresponds to a street location, the icon moves along a particular street on the raster map display. However, because the raster map is merely a digitized representation of the street, no interrelationship between different street locations or landmarks exists. Thus although the MapStation can display latitude and longitude information, it cannot display intelligent street information such as the particular street the vehicle is traveling on or the proximity of the vehicle to a particular street or landmark.
FIG. 2 shows a block diagram of a prior art raster map display system 200 comprised of: a Mobile Position Database 210, a Mobile Position Utility Library 212, a Raster Database 214, a Raster Map Utility Library 216, an Interface Utility Library 218, and a Raster Display 220. The Mobile Position Library 212 contains routines which access the Mobile Database 210 retrieving vehicle identification, latitude and longitude information. The latitude and longitude values of the vehicle are transmitted to the Raster Utility 216 via bus 222. In response, the Raster Utility 216 accesses the Raster Database 214 and extracts a latitude and longitude value for the particular vehicle. The latitude, longitude and vehicle identification values are passed to the Interface Utility 218 where they are used for display of an icon on the Raster Display 220. In addition, the Raster Utility 216 extracts digitized information for a defined area based on the fleet location and zoom level for display as a raster map on the Raster Display 220.
FIG. 3 illustrates a vector map display. FIG. 4 illustrates a block diagram of the display system for implementing the vector map display shown in FIG. 3. Unlike the Raster Map Database shown in FIG. 2, the Vector Map Database 414 contains street and address information that provides the computer with the capability to identify the address of a vehicle location. The address information could consist of the block number, street name, county information. The vector display is generated in a similar manner to the raster display previously discussed. Streets in the Vector Map Database 414 are defined in terms of segments. Segments are interconnected so that streets are interrelated to each other.
However, although the vector map contains street information, it does not contain visual features. Thus such as natural features of the land, contour lines featuring shape and elevation and specific features such as towns, water areas and vegetation which are typically displayed on a raster map are not shown on a vector display map.
Because visual features are so important to the dispatcher, one vector map display system created by Etak Corporation has tried to simulate the visual features such as landmarks commonly found in raster type display systems. The Etak system creates a stick-like outline of the landmark. Although the landmark is represented, the quality of the representation is inferior to the representation of the raster display.
Assimilating vehicle location as quickly as possible for efficient decision making is of prime importance. The majority of users are familiar with the road-map type display of raster displays and prefer digitized raster maps for being able to quickly recognize vehicle position. Because raster maps include geographic landmarks and visual features not found in the stick-like interconnection presented by vector maps, it is often easier to find or to designate a vehicle position. Additionally, users are accustomed to describing vehicle location as being a certain distance from a school, building or other landmark. However, although users are often more comfortable determining vehicle position using a raster map, raster maps are incapable of providing intelligent street information valuable in decision making. For example, a dispatcher would not be provided with information related to the distance between the current vehicle position and the vehicle destination using information provided by a raster data display system.
An integrated system for providing a raster map display which also provides intelligent address information is needed.